This massive patch-series has been a long time coming for allowing FP64 support on Haswell, as up to now only Broadwell and newer have supported this extension for exposing double-precision floating-point data types. This has also been the lone extension blocking Haswell from having OpenGL 4.0+ support with the Mesa Linux driver.
Waking up this morning, it was exciting to see the massive set of patches finally pushed to mainline, concluding with flipping the bit for turning on FP64 for Haswell. In late December was when I had just written that it looked like the code may finally land after being tied up in review for months.
But while this extension is now on, the i965 Mesa driver isn't yet exposing GL4 for Haswell. Iago Toral Quiroga of Igalia sent out these separate six patches this morning for actually enabling OpenGL 4.0 on Haswell. This is done due to some hardware and kernel combinations not supporting all of the features for OpenGL 4.0. In the end, on supported combinations, it enables OpenGL 4.0 for Haswell but not anything higher (some had previously talked of Haswell going straight to GL 4.3~4.5 when FP64 landed).